1. Field of the Invention
The present invention relates to a method for shielding a stream of liquid metal against oxidation and/or nitriding when it is being poured from a first receptacle such as a ladle, a distributor, or the like into a second receptacle such as a tundish, an ingot mold, or the like, the pouring stream of liquid metal being surrounded by a screen of shielding gas which prevents or reduces oxidation and/or nitriding by the surrounding atmosphere.
2. Description of the Prior Art
It is known from European Pat. No. EP 154 585 to shield a stream of metal with carbon dioxide, for example during pouring from a ladle into an ingot mold. The ladle is preferably provided with a peforated, circular ring which is located just above the pouring spout and is capable of forming a shielding screen of carbon dioxide gas. The ring is connected to a continuous feeder source of carbon dioxide gas. The installation further comprises conventional equipment to blow out the ingot mold using gaseous carbon dioxide.
It is also known from European Pat. No. EP 196 952 to inert a casting ladle by injecting carbon dioxide snow into the bottom of the ladle before and, if necessary, during the pouring of the metal stream into the ladle.
These two methods pertain more especially to the pouring of a liquid metal into a ladle or an ingot mold and are not directly applicable to continuous casting from a ladle into an oscillating ingot mold, for example. Moreover, the use of gaseous carbon dioxide in the first patent referred to above necessitates vaporizer between the storage of liquid carbon dioxide and the means used to inject gaseous carbon dioxide.